In the recent past, individuals and businesses typically received telephone calls on a landline at their home or business. Times are changing, and not only do many people now carry a mobile telephone with them for personal use or for business, but also there is an increase in unwanted spam telephone calls. This combination of ubiquitous telephones and an increase in spam means that the average person is bothered more and more by unwanted telephone calls that may be received at any time and in any place.
A person may use various techniques to avoid these unwanted calls, but none are optimal. By default, many people simply decide to always answer their telephone wherever they are and whenever it rings; but, this technique can be very inconvenient, frustrating, and can waste time when many of the calls are unwanted. Others might choose to only give out their telephone number to select individuals, but this technique may prevent the individual from receiving important calls from legitimate callers. (And, it is probably inevitable that a spammer will eventually get hold of these secret telephone numbers.) Still others choose to screen their incoming calls (listening to the call until they decide to answer it or not), but this can be annoying for legitimate callers and embarrassing for the receiver. Those that use a caller identification device on their telephone to screen calls may miss calls from legitimate callers that just happen to be calling from an unfamiliar telephone number. Some people choose never to answer their telephone, forcing all callers (legitimate or not) to leave a message. While this technique might thwart certain spammers, it is annoying for legitimate callers and is somewhat inconvenient for the receiver in that they can no longer accept calls immediately.
Therefore, an improved technique is desired that would block or prevent unwanted telephone calls, yet still allow legitimate callers to reach an individual. Such an improved technique should not be burdensome for the callers, yet should still allow a receiver to receive calls promptly.